1. Field of the Invention
The present invention relates to a wireless LAN (Local Area Network) system, a communication terminal, a LAN control apparatus and QoS (Quality of Service) control method, and, more particularly, to techniques for QoS setting and renewal which should be carried out on a terminal side to be connected to a wireless LAN and for QoS control.
2. Description of the Related Art
With an increase in the usage of communication networks typified by the Internet, a LAN environment that supports communication networks are expanding to various areas including the ordinary usages in offices and homes. In predetermined public areas such as a cafe and hotels, particularly, a wireless LAN connection service called “Hotspot” (registered trademark) using IEEE802.11b (the standard for a wireless LAN using 2.4-GHz band) and IEEE802.11a (the standard for a wireless LAN using 5.2-GHz band) (hereinafter simply called “Hotspot”) has already started.
A user who receives a wireless LAN service typified by such a Hotspot establishes connection to an access point (called “parent device” or simply “parent”) sited in a public area using a notebook type PC (Personal Computer), PDA (Personal Digital Assistant) or the like equipped with a wireless LAN terminal (called “child device” or simply “child”) and can communicate with another communication network such as the Internet through the access point.
One possible case of using LAN environments over an office, a home and various public areas is that a user, such as a business person who mainly works in suburbs always carrying around a business terminal, such as a notebook type PC or PDA, connectable to a wireless LAN uses an office LAN in an office, a domestic LAN in a home and countless Hotspots in fields using the business terminal.
In the mentioned case, the LAN environments which are used by a single terminal are not limited to an office and a home, but extend to various other areas, such as countless Hotspots. In this case, a user needs to set a LAN environment for each LAN, so that as the number of LANs increases, the operation and process become more complicated. This problem becomes noticeable particularly in such a case where a QoS to guarantee the quality of communication of communication data is set.
With regard to QoS setting in such a communication network like LAN, there have been proposed a networks connecting apparatus which guarantees the optimal QoS at the time of connecting a LAN and ATM (Asynchronous Transfer Mode) network together (see JP-A-2000-341343) and a LAN switch which performs such control as to separate a communication traffic to a control packet and a data packet, classify the communication traffic for each QoS setting, extract the control packet before executing priority control and treat it in the same way as a data packet traffic with the highest priority (see JP-A-2001-094605).
However, the conventional techniques described in JP-A-2000-341343 and JP-A-2001-094605 are not necessarily premised on the use of multifarious LAN environments over various areas using a single terminal as mentioned in the above-described case, and do not overcome the problem arising from the manual setting of LAN environments including the QoS setting.
Particularly, in case that a user moves to a LAN with a different QoS policy, the user cannot receive benefit of the QoS unless the user check the QoS setting of the LAN at the destination beforehand. Further, as there are different QoS settings in various LANs which are used in a home, an office, countless Hotspots and so forth, the settings cannot be managed automatically. Because there are different security settings and account settings in such various LANs, those settings cannot be managed automatically as in the case of the QoS settings.